Experimental verification of models assessing Eh evolution induced by corrosion of carbon steel overpack

Corrosion experiments of a carbon steel plate embedded in bentonite mixture were conducted to verify our models assessing Eh evolution induced by corrosion of carbon steel overpack. The experimental results showed that the Eh decreased for the first 200 days and was subsequently stabilised at around −450 mV; corrosion products were identified as magnetite and Fe was present mostly as divalent Fe within a 5 mm range from the carbon steel plate. Reactive transport modelling was performed to assess the Eh evolution in the system using kinetic dissolution model for metallic iron and thermodynamic equilibrium models for other chemical reactions and closely reproduced the experimental results. The models were verified only under the conditions employed in this study.